Audio level adjustment of some electronic devices, such as portable two-way radios, may be achieved by rotating a knob which is coupled to a potentiometer of an audio control assembly. Generally, the knob is engaged to a rotating shaft, wherein rotating the knob increases or decreases the audio power delivered to a speaker. In some applications, it is desired to add a secondary function, such as a switching function, in order to provide additional operational features for the radio. For example, the radio may transmit an emergency signal when a user activates the switching function. However, the limitations imposed by the size of the radio may make addition of a separate or an integral switch on the radio housing difficult and even impossible. It is therefore, desirable to add the switching function to the embodiment of the audio control assembly.
Conventional dual function switches are used on a number of applications, such as car radios or home stereos, where the dual function may comprise switching from a first potentiometer function to a secondary potentiometer function or an on/off function. The secondary function is generally activated by pulling or pushing on the potentiometer shaft. In this arrangement, the secondary function is activated regardless of the rotational position of the rotary shaft.
However, in some applications, such as the above example, in order to minimizes the chances of inadvertent actuation emergency signal transmission by the user, it is desirable for the switching action to occur only when the rotary shaft of the assembly is in a predetermined position. Accordingly, it may be desired to activate the secondary function of the dual function assembly only when the rotary shaft is in a predetermined position.